Remove the SkCanvas comment API

src/pipe/SkGPipeWrite.cpp

Index: src/pipe/SkGPipeWrite.cpp
diff --git a/src/pipe/SkGPipeWrite.cpp b/src/pipe/SkGPipeWrite.cpp
index 7f8d61ca9fcd0e00d51fb9b6b3f47ca0c8b2b75b..9fd81b05eb33e046678c6673932f6dc90242e8d4 100644
--- a/src/pipe/SkGPipeWrite.cpp
+++ b/src/pipe/SkGPipeWrite.cpp
@@ -238,10 +238,6 @@ public:
         return bytesAllocated;
     }
 
-    void beginCommentGroup(const char* description) override;
-    void addComment(const char* kywd, const char* value) override;
-    void endCommentGroup() override;
-
     /**
      * Flatten an SkBitmap to send to the reader, where it will be referenced
      * according to slot.
@@ -1146,18 +1142,6 @@ void SkGPipeCanvas::onDrawPatch(const SkPoint cubics[12], const SkColor colors[4
     }
 }
 
-void SkGPipeCanvas::beginCommentGroup(const char* description) {
-    // ignore for now
-}
-
-void SkGPipeCanvas::addComment(const char* kywd, const char* value) {
-    // ignore for now
-}
-
-void SkGPipeCanvas::endCommentGroup() {
-    // ignore for now
-}
-
 void SkGPipeCanvas::flushRecording(bool detachCurrentBlock) {
     this->doNotify();
     if (detachCurrentBlock) {